EP4012834B1 - Antenna source for an array antenna with direct radiation, radiating panel and antenna comprising a plurality of antenna sources - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION

The invention is located in the field of satellites and more particularly for satellites in low orbit which must transmit data everywhere on the Earth, in particular in the K and Ka bands (the K and Ka bands are grouped together in space telecommunications), in the Ku band, or even in the V band. The invention can find an application for example for high-speed internet.

The Ka band corresponds to a frequency band between 27 and 40 GHz. It is used in particular for satellite Internet. For space telecommunications, and according to the definition of the ITU (International Telecommunications Union), the Ka band is grouped with the K band and extends in reception from 27.5 to 30 GHz and in transmission from 17.7 to 20.2GHz.

According to the ITU definition, and for space telecommunications, the V band is divided into two frequency bands: the Q band (37.5-42.5 GHz) and the V band (47.2 - 50.2 GHz), with smaller dimensions. Table 1 Literal symbol Use for radar (GHz) Space radiocommunications Spectrum regions Examples Nominal designation Examples (GHz) L 1-2 1.215-1.4 1.5 GHz band 1,525-1,710 S 2-4 2.3-2.5 2.5 GHz band 2.5-2.690 2.7-3.4 VS 4-8 5.25-5.85 4/6 GHz band 3.4-4.2 4.5-4.8 5.85-7.075 X 8-12 8.5-10.5 - - Ku 12-18 13.4-14.0 11/14 GHz band 10.7-13.25 15.3-17.3 12/14 GHz band 14.0-14.5 K ⁽¹⁾ 18-27 24.05-24.25 20 GHz band 17.7-20.2 Ka ⁽¹⁾ 27-40 33.4-36.0 30 GHz band 27.5-30.0 V - - 40 GHz band 37.5-42.5 47.2-50.2 ⁽¹⁾ In space radiocommunications, the K and Ka bands are often designated by the single symbol K _a .

The invention relates more precisely to the field of space antennas for satellites in low orbit where data must be transmitted in a large angular range, and in particular direct radiation array antennas. What is meant here by “direct radiation array antenna” or “DRA” in English is an antenna that can operate in transmission and/or reception and comprising a network of elementary radiation sources connected by a beamformer (called “BFN” for “ Beam Forming Network” in English).

STATE OF THE ART

Two types of orbiting satellites can be used to provide broadband on Earth.

A first type concerns geostationary satellites (36,000 km) which will make it possible to provide broadband on Earth in a given region or area. In this orbit the satellite moves exactly synchronously with the Earth and remains constantly above the same point on the surface.

A second type is based on the use of a constellation of satellites in low orbit (called “LEO” satellites for “Low Earth Orbit” in English) configured to provide broadband throughout the Earth. A satellite constellation is a collection of artificial satellites that work together. The satellites orbit in selected, synchronized orbits so that their respective ground coverage overlaps and complements each other instead of interfering with each other. One of the advantages of the low orbit satellite constellation is the latency time between transmission and reception of data because the low orbit satellites used are closer to the earth (generally between 500 and 1200 km). The reduction in latency time is an advantage for areas requiring a very rapid response (for example: for an autonomous car, for faster access to data, for video calls or videoconferences with better responsiveness, etc.). The Earth is seen from the LEO satellite following a cone which can vary between +/- 45° and +/- 55° depending on the altitude of the satellite. This field is in strong development, with numerous missions and/or satellite constellation projects in low orbit (Starlink, Kuiper, Télésat, Leosat, Oneweb, etc.). The data transmitted between these satellites and the Earth for high-speed internet communications use the Ka bands (grouping K and Ka for space), the Q and V bands but also the Ku band. It is therefore sought for antennas that can operate in these bands and in particular in the Ka band.

The antenna generally used for LEO satellites is a direct radiating array antenna called “DRA” (“Direct Radiating Array” in English which is translated into French as “direct radiation network”).

DRA antennas in the field of the invention, for example WO2020/194270 A1 , have a large number of sources (generally from 128 to 512 sources) and each source is composed of at least one radiating element, a polarizer and a filter which must easily connect to the amplifiers (or loads). All the sources form a radiating panel. An elementary radiating element of a DRA antenna must have an opening of small size in relation to its operating frequency (we are talking about dimensions of the order of 0.55 to 0.7 λ with λ=c/ f where λ is the wavelength, c the speed of propagation of the wave, and f represents the maximum operating frequency of the antenna. This is in order not to emit a spurious signal (network lobe) on another area of the earth which would degrade the performance of the system. This generates very small sources, of the order of 5 to 9 mm in diameter in Ka band.

• être facile à fabriquer, notamment pour minimiser le coût ;
• comporter le moins de pertes RF possibles, en particulier pour avoir le moins de puissance à dissiper dans une petite surface ;
• être le plus compact possible pour limiter la masse ;
• faciliter la connexion aux amplificateurs.

It is generally desired that sources respect the following constraints:

• be easy to manufacture, particularly to minimize cost;
• have the least possible RF losses, in particular to have the least power to dissipate in a small area;
• be as compact as possible to limit mass;
• facilitate connection to amplifiers.

There are DRA antennas called “printed antennas” or “patch antennas”, allowing the transmission of data between LEO satellites and the Earth. They include elements (or “patches”) printed on a flat substrate, and are suitable for frequency bands such as L band or S band, which are lower than the Ka band and for low bandwidths (less than 1 %). The sources (radiating element, polarizer, filter) of these antennas are manufactured using printed circuit type technology, so they are easily manufactured, they are compact and of limited mass. Losses are not prohibitive in frequency bands such as L band or S band. In addition, patch antennas are well suited for low bandwidths (less than 1%).

On the other hand, for larger frequency bands (Ka band for example), printed antennas are no longer suitable, or otherwise it is necessary to stack several small patches on a substrate, which on the one hand is limited or difficult to achieve. And on the other hand, even by stacking the patches, the RF losses become too high in these frequency bands (around 2 dB with a substrate for the Ka band), at least due to the presence of the substrate. These losses are prohibitive for space applications; we avoid dissipating power unnecessarily in this environment where the available energy is very limited.

There are other antennas in which the radiating elements are based on horn waveguides loaded with dielectric or even on so-called “riddled” horn waveguides as described for example in the publication “A compacted dual linearly polarization wideband feed for parabolic reflector antenna” Wen-Juan Ye et al. The term “riddled waveguide” is defined as a waveguide of any shape (square, circular, rectangular) capable of transmitting a microwave signal and comprising one or more ribs inside it. The problem with the waveguide radiating element with a horn shape, whether wrinkled or not, is that it requires a system to circularly polarize the wave. As the size of the radiating element is in the range of 0.55 to 0.7 λ, a diverter is generally used to connect the horn to the system which allows the wave to be circularly polarized. In fact, systems of the OrthoMode transducer (OMT) type with coupler or septum polarizer as a guide do not respect this mesh or size constraint. The diverter allows, with a set of waveguides (as many as the number of radiating elements) which are curved, to change the size of a mesh between its entrance and its exit. The major constraint consists of having guides of identical lengths. This constraint implies that the diverter is difficult to design. In addition, the use of a diverter implies a much larger footprint for the radiating panel and significant RF losses due to the diverter. In addition, a diverter structure is difficult to produce in a single part, even using an additive manufacturing technique.

The invention aims to overcome the aforementioned drawbacks of the prior art.

More particularly it aims to have an antenna source to produce a DRA network antenna, a source which is as compact as possible, which generates circular polarization without using a diverter, which is adapted for the Ka frequency band (or K, Q, V, Ku ...), whose elementary radiating element has a small aperture compared to the wavelength λ, and which has low RF losses (typically less than 0.3 dB, or even 0.2 dB an Ka band). Furthermore, the invention aims to have such an antenna source which can integrate a filter and which can easily connect to an amplifier. Finally, the antenna source must be able to be manufactured easily and at low cost.

STATEMENT OF THE INVENTION

• la partie principale du guide d'onde comprenant dans ladite direction longitudinale :
  • une première portion formant un élément rayonnant, ou la majeure partie d'un élément rayonnant, ledit élément rayonnant comprenant des premières nervures s'étendant vers l'intérieur et sur tout ou partie de la longueur dudit élément rayonnant, lesdites premières nervures étant régulièrement réparties autour du périmètre dudit élément rayonnant et présentant plusieurs marches le long de la direction longitudinale, le nombre, les hauteurs et les épaisseurs desdites marches étant configurées pour permettre une variation, de préférence une augmentation, d'impédance donnée entre l'entrée et la sortie de l'élément rayonnant ;
  • une deuxième portion formant un polariseur, ledit polariseur comportant deux entrées séparées par une lame interne s'étendant selon la direction longitudinale et une sortie correspondant à l'entrée de l'élément rayonnant, la lame interne comportant plusieurs paliers le long de la direction longitudinale (X), lesdits paliers étant configurés pour transformer un champ électromagnétique de polarisation circulaire en entrée en un champ électromagnétique de polarisation linéaire en sortie, et inversement pour transformer un champ électromagnétique de polarisation linéaire en sortie en un champ électromagnétique de polarisation circulaire en entrée, le polariseur comprenant en outre des deuxièmes nervures s'étendant vers l'intérieur et sur toute ou partie de la longueur dudit polariseur, lesdites deuxièmes nervures et ladite lame interne étant régulièrement réparties autour du périmètre dudit polariseur ;
• l'élément rayonnant et le polariseur étant en une seule pièce, de préférence réalisée selon une technique de fabrication additive, et étant disposés bout à bout dans la direction longitudinale.

A first object of the invention making it possible to remedy these drawbacks is an antenna source for a direct radiation array antenna, called a DRA antenna, for the transmission and reception of microwave waves, said source comprising a waveguide having at least one main part in the form of a hollow straight cylinder extending in a longitudinal direction, the base of said cylinder having at least one axis of symmetry in its plane and the external transverse dimensions of said main part being constant in the longitudinal direction;

• the main part of the waveguide comprising in said longitudinal direction:
  • a first portion forming a radiating element, or the major part of a radiating element, said radiating element comprising first ribs extending inwards and over all or part of the length of said radiating element, said first ribs being regularly distributed around the perimeter of said radiating element and having several steps along the longitudinal direction, the number, heights and thicknesses of said steps being configured to allow a variation, preferably an increase, of given impedance between the input and the output of the radiating element;
  • a second portion forming a polarizer, said polarizer comprising two inputs separated by an internal blade extending in the longitudinal direction and an output corresponding to the input of the radiating element, the internal blade comprising several bearings along the longitudinal direction (X), said bearings being configured to transform an electromagnetic field of circular polarization at the input into an electromagnetic field of linear polarization at the output, and vice versa to transform an electromagnetic field of linear polarization at the output into an electromagnetic field of circular polarization at the input, the polarizer further comprising second ribs extending inwards and over all or part of the length of said polarizer, said second ribs ribs and said internal blade being regularly distributed around the perimeter of said polarizer;
• the radiating element and the polarizer being in one piece, preferably produced using an additive manufacturing technique, and being arranged end to end in the longitudinal direction.

By arranged “end to end”, we mean that the elements are joined at their ends.

According to a preferred embodiment, the waveguide has a constant thickness over its entire length.

It is specified that the impedance between the input and output of the radiating element generally increases between a hundred ohms (in the waveguide) and 377 ohms (in air or vacuum).

By “cylinder” or “cylindrical”, we mean the general definition, namely a solid generated by a straight line which moves parallel to an axis, based on two fixed isometric and parallel planes. A right cylinder designates a cylinder whose generators are perpendicular to the bases. The base can be a circle or a polygon (square, hexagon, octagon, decagon...). In the case where the base is a polygon, we can also speak of a prism. The base must have an axis of symmetry in its own plane. This is why we will speak of a polygon of even order (that is to say with an even number of sides).

By “polarizer” is meant an element intended to convert, on the one hand, the signals received in circular polarization into signals in linear polarization and, on the other hand, the signals to be transmitted from a linear polarization to a circular polarization.

The terms “input” or “output” are defined according to the direction of circulation of the radiofrequency (RF) waves in the source when it operates in transmission, that is to say from the filter or the polarizer towards the horn.

A radiating element may be designated by “horn” which is a term commonly used in the field of the invention and which designates an antenna element in the shape of a cylinder, and which may comprise a complementary part in the shape of a cone or pyramid. truncated. In the case of a horn comprising a complementary part in the shape of a cone or truncated pyramid, the most flared part always corresponds to the outlet of the radiating element.

A waveguide comprising ribs inside said waveguide may be referred to as a “riddled waveguide”.

According to the invention, for all the elements constituting the antenna source, the term “length” is to be understood with reference to the longitudinal direction of the antenna source. The term “radial” is to be understood by reference to a plane perpendicular to said longitudinal direction, called “transverse plane”, and the term “orthoradial” designates the direction perpendicular to the radial direction in said transverse plane. The width of the blade designates the radial dimension of the blade, more generally the dimension of the blade which allows the polarizer input to be separated in two. The thickness of the blade designates the other dimension in the transverse plane. The height of a rib designates the radial dimension. The thickness of a rib designates the dimension in the orthoradial direction. The height of a stud designates the dimension substantially in the radial direction and the thickness of a stud designates the dimension substantially in the orthoradial direction.

The solution consists of forming a radiating element in waveguide with internal ribs, and a polarizer in waveguide with septum and internal ribs connected to the radiating element in continuity with it (in a single piece) , the septum polarizer allowing two waveguide accesses. A ribbed waveguide pad filter can be placed on one of the polarizer ports.

Thus, the antenna source integrates a radiating element with internal ribs compatible with a very low DRA array antenna mesh (0.5 to 0.7 λ), but also a low-loss septum polarizer compatible with the same mesh. DRA network antenna, and which generates circular polarization without using a diverter.

• d'avoir une source élémentaire (cornet, polariseur, plus éventuellement un filtre) qui reste dans la maille (gain en masse et en compacité) ;
• de conserver une technologie guide (et non patch) pour réduire les pertes, même en bande Ka (et aussi en bande K, Ku, Q, V ...);
• d'être réalisable à faible coût, en particulier par une technique de fabrication additive ;
• de se connecter facilement aux amplificateurs et/ou charges de l'antenne, comme décrit plus après.

The solution thus allows:

• to have an elementary source (horn, polarizer, plus possibly a filter) which remains in the mesh (gain in mass and compactness);
• to maintain a guide technology (and not a patch) to reduce losses, even in Ka band (and also in K, Ku, Q, V bands, etc.);
• to be achievable at low cost, in particular by an additive manufacturing technique;
• to easily connect to antenna amplifiers and/or loads, as described later.

The antenna source according to the invention may also include one or more of the following characteristics taken in isolation or in any possible technical combination.

The number of first ribs and/or second ribs is preferably an even number, both at the input and output of the radiating element and/or the polarizer. An even number favors symmetry of the antenna source. The even number also favors the introduction of the blade of the septum polarizer which in this case attaches to two opposite ribs and makes it possible to simplify the dimensioning of the septum polarizer.

The second ribs can be in continuity with the first ribs at the entrance to the radiating element (corresponding to the last step), which facilitates the design and manufacture of the source. Alternatively, the second ribs may not be in continuity with the first ribs at the entrance to the radiating element.

According to one embodiment, the base of the right cylinder is a regular polygon of even order, preferably a hexagon.

According to a first variant, the internal blade and all or part of the first ribs and/or the second ribs can be arranged at the level of the edges of the straight polygonal cylinder.

According to a second variant, the internal blade and all or part of the first ribs and/or the second ribs can be arranged on the interior lateral surfaces of the straight polygonal cylinder.

The first and second variants can be combined such that the internal blade can be arranged at two opposite edges of the straight polygonal cylinder or on two opposite interior side surfaces of the straight polygonal cylinder, and the first ribs and/or the second ribs can be arranged both at the edges of the straight polygonal cylinder and on the interior side surfaces of the straight polygonal cylinder.

According to an alternative embodiment, the base of the right cylinder is a circle.

• une troisième portion comprenant un filtre, la lame interne étant prolongée dans toute ou partie de ladite troisième portion, ledit filtre comprenant un ensemble de plots de filtration en fréquence disposés à l'intérieur de la troisième portion et sur une seule et même surface de la lame interne, la sortie du filtre correspondant à une des deux entrées du polariseur, ladite troisième portion comprenant en outre des troisièmes nervures s'étendant vers l'intérieur et sur tout ou partie de la longueur de ladite troisième portion, lesdites troisièmes nervures et la lame interne étant régulièrement réparties autour du périmètre de ladite troisième portion ;

l'élément rayonnant, le polariseur et le filtre étant en une seule pièce, de préférence réalisée selon une technique de fabrication additive, et le polariseur et le filtre étant disposés bout à bout dans la direction longitudinale.The antenna source further includes:

• a third portion comprising a filter, the internal blade being extended in all or part of said third portion, said filter comprising a set of frequency filtration pads arranged inside the third portion and on one and the same surface of the internal blade, the output of the filter corresponding to one of the two inputs of the polarizer, said third portion further comprising third ribs extending inwards and over all or part of the length of said third portion, said third ribs and the internal blade being regularly distributed around the perimeter of said third portion;

the radiating element, the polarizer and the filter being in one piece, preferably produced using an additive manufacturing technique, and the polarizer and the filter being arranged end to end in the longitudinal direction.

Preferably, the number of third ribs is an even number, and both at the inlet and outlet of the filter. An even number favors symmetry of the antenna source.

The third ribs can be continuous with the second ribs of the polarizer, which facilitates the design and manufacture of the source. Alternatively, the third ribs may not be continuous with the second ribs.

According to one embodiment, the waveguide is entirely in the shape of a hollow straight cylinder over its entire length. In other words, the main part represents the entire length of the waveguide.

According to an alternative embodiment, the waveguide comprises a main part in the shape of a hollow right cylinder and a complementary part at the outlet of the radiating element, said complementary part being able to be in the shape of a cone or truncated pyramid, the most flared part being arranged at the outlet of the radiating element. The complementary part is free of grooves. Furthermore, the length of the complementary part is very small compared to the length of the main part of the waveguide.

A second object of the invention is a radiating panel for a direct radiating array antenna, said panel comprising a plurality of sources according to the invention comprising a plurality of antenna sources according to the first object of the invention; said radiating panel being in a single piece, preferably produced using an additive manufacturing technique.

Preferably, the sources of the same radiating panel are all substantially identical.

The radiating panel comprises sources each having small-sized radiating elements (0.5 to 0.7 λ) with very low RF losses (typically less than 0.3 dB, or even 0.2 dB in Ka band) and is easily manufactured.

• un panneau rayonnant selon le deuxième objet de l'invention;
• au moins un amplificateur et/ou une charge connecté au panneau rayonnant, au niveau de l'entrée d'au moins un filtre et/ou d'une entrée d'au moins un polariseur.

A third object of the invention is a direct radiation array antenna, called a DRA antenna, comprising:

• a radiating panel according to the second object of the invention;
• at least one amplifier and/or a load connected to the radiating panel, at the input of at least one filter and/or an input of at least one polarizer.

According to an advantageous embodiment, the radiating panel is connected to the at least one amplifier and/or the at least one load via at least one Vivaldi antipodal transition, and preferably by at least one adapted transition/adaptation to change the position, dimensions and/or shape of the ribs of the waveguide at the input of the source so as to be able to position the Vivaldi transition within said waveguide.

The antenna source, the radiating panel and the direct radiation array antenna according to the invention may comprise any of the characteristics previously stated, taken in isolation or in any technically possible combination with other characteristics.

BRIEF DESCRIPTION OF THE FIGURES

• [Fig.1A] et
  [Fig.1B] représentent une source d'antenne selon un premier mode de réalisation de l'invention (mode de realisation non couvert par les revendications annexées).
• [Fig.2A],
  [Fig.2B],
  [Fig.2C] et
  [Fig.2D] représentent une source d'antenne selon un deuxième mode de réalisation de l'invention.
• [Fig.3A] et
  [Fig.3B] représentent en détail un cornet hexagonal selon une première variante de l'invention.
• [Fig.4A],
  [Fig.4B] et
  [Fig.4C] représentent en détail un polariseur hexagonal selon la première variante de l'invention.
• [Fig.5A],
  [Fig.5B] et
  [Fig. 5C] représentent en détail un filtre selon la première variante de l'invention.
• [Fig.6A] et
  [Fig.6B] représentent en détail un cornet hexagonal selon une deuxième variante de l'invention.
• [Fig.7A],
  [Fig.7B] et
  [Fig.7C] représentent en détail un polariseur hexagonal selon la deuxième variante de l'invention.
• [Fig.8] représente en détail un cornet hexagonal selon une troisième variante de l'invention.
• [Fig.9A] et
  [Fig.9B] représentent en détail un cornet circulaire selon une quatrième variante de l'invention.
• [Fig.10A],
  [Fig.10B] et
  [Fig.10C] représentent en détail un polariseur circulaire selon la quatrième variante de l'invention.
• [Fig.11] illustre plusieurs formes de filtres pour une source selon l'invention.
• [Fig.12A],
  [Fig.12B] et
  [Fig.12C] illustrent plusieurs transitions optionnelles entre le filtre et le polariseur pour une source selon l'invention.
• [Fig.13] représente en vue 3D un panneau rayonnant pour une antenne réseau à rayonnement direct comprenant une pluralité de sources selon l'invention.
• [Fig.14A] et
  [Fig.14B] illustrent un mode particulier de réalisation d'un filtre d'une source selon l'invention.
• [Fig.15A] et
  [Fig.15B] illustrent un mode particulier de réalisation d'un élément rayonnant selon l'invention.
• [Fig.16] schématise une architecture fonctionnelle d'une antenne réseau à rayonnement direct.
• [Fig.17] illustre un premier mode de connexion entre un panneau rayonnant et des amplificateurs et/ou des charges.
• [Fig.18] illustre un deuxième mode de connexion entre un panneau rayonnant et des amplificateurs et/ou des charges.
• [Fig.19A] et
  [Fig.19B] sont des schémas de principe d'une transition Vivaldi.
• [Fig.20A],
  [Fig.20B] et
  [Fig.20C] illustrent une adaptation/transition du guide d'onde d'une source selon l'invention permettant d'intégrer une transition Vivaldi vers des amplificateurs et/ou des charges.
• [Fig. 21] illustre un guide d'onde d'une source selon l'invention intégrant une transition Vivaldi vers des amplificateurs et/ou des charges.

Other characteristics, details and advantages of the invention will emerge on reading the description made with reference to the appended drawings given by way of example and which represent, respectively:

• [ Fig.1A ] And
  [ Fig.1B ] represent an antenna source according to a first embodiment of the invention (embodiment not covered by the appended claims).
• [ Fig.2A ],
  [ Fig.2B ],
  [ Fig.2C ] And
  [ Fig.2D ] represent an antenna source according to a second embodiment of the invention.
• [ Fig.3A ] And
  [ Fig.3B ] represent in detail a hexagonal horn according to a first variant of the invention.
• [ Fig.4A ],
  [ Fig.4B ] And
  [ Fig.4C ] represent in detail a hexagonal polarizer according to the first variant of the invention.
• [ Fig.5A ],
  [ Fig.5B ] And
  [ Fig. 5C ] represent in detail a filter according to the first variant of the invention.
• [ Fig.6A ] And
  [ Fig.6B ] represent in detail a hexagonal horn according to a second variant of the invention.
• [ Fig.7A ],
  [ Fig.7B ] And
  [ Fig.7C ] represent in detail a hexagonal polarizer according to the second variant of the invention.
• [ Fig.8 ] represents in detail a hexagonal horn according to a third variant of the invention.
• [ Fig.9A ] And
  [ Fig.9B ] represent in detail a circular horn according to a fourth variant of the invention.
• [ Fig.10A ],
  [ Fig.10B ] And
  [ Fig.10C ] represent in detail a circular polarizer according to the fourth variant of the invention.
• [ Fig.11 ] illustrates several forms of filters for a source according to the invention.
• [ Fig.12A ],
  [ Fig.12B ] And
  [ Fig.12C ] illustrate several optional transitions between the filter and the polarizer for a source according to the invention.
• [ Fig.13 ] represents in 3D view a radiating panel for a direct radiation array antenna comprising a plurality of sources according to the invention.
• [ Fig.14A ] And
  [ Fig.14B ] illustrate a particular embodiment of a filter of a source according to the invention.
• [ Fig.15A ] And
  [ Fig.15B ] illustrate a particular embodiment of a radiating element according to the invention.
• [ Fig.16 ] schematizes a functional architecture of a direct radiation array antenna.
• [ Fig.17 ] illustrates a first mode of connection between a radiating panel and amplifiers and/or loads.
• [ Fig.18 ] illustrates a second mode of connection between a radiating panel and amplifiers and/or loads.
• [ Fig.19A ] And
  [ Fig.19B ] are block diagrams of a Vivaldi transition.
• [ Fig.20A ],
  [ Fig.20B ] And
  [ Fig.20C ] illustrate an adaptation/transition of the waveguide of a source according to the invention making it possible to integrate a Vivaldi transition towards amplifiers and/or loads.
• [ Fig. 21 ] illustrates a waveguide of a source according to the invention integrating a Vivaldi transition to amplifiers and/or loads.

In all of these figures, identical references can designate identical or similar elements.

Furthermore, the different parts represented in the figures are not necessarily on a uniform scale, to make the figures more readable.

DETAILED DESCRIPTION OF THE INVENTION

In the detailed description, the radiating element may be designated by the term "horn".

The longitudinal direction is marked by the reference X and the arrow is oriented in the direction of entry towards exit of each of the elements (horn, polarizer, filter). The longitudinal direction X also corresponds to the cylinder axis. The polarizer is arranged end to end with the horn in the longitudinal direction, and the filter, if applicable, is arranged end to end with the polarizer in the longitudinal direction.

For all of the modes and variants presented in the remainder of the description, and more generally according to the invention, the antenna source can be made of metallic, metallized, or metallizable material. For example, it may be aluminum, titanium, or any other material which can be metallized on the surface. Preferably, the material of the antenna source is suitable for manufacturing the antenna source, and for manufacturing the radiating panel of the array antenna. (comprising a plurality of sources in a single part) by an additive manufacturing technique.

According to the invention, a source comprises a waveguide having at least one main part in the form of a hollow straight cylinder extending in a longitudinal direction X, the base of said cylinder having at least one axis of symmetry in its plane. The external transverse dimensions of this main part are constant in the longitudinal direction X. In the remainder of the detailed description, it is agreed that the shape of the source corresponds to the shape of the waveguide.

The sources represented in the figures and described in the following description are in the shape of a hollow right cylinder, over their entire length (in other words, the main part extends over the entire length of the guide). wave).

Alternatively, according to a variant embodiment not shown, the source may comprise, at the outlet of the radiating element, a complementary part in the shape of a cone or truncated pyramid, the most flared part being arranged at the outlet of the radiating element. Instead of a cone or a truncated pyramid, the source may comprise, at the outlet of the radiating element, a complementary part of cylindrical shape with external transverse dimensions and/or basic shape different from the main part. The complementary part is free of grooves. In addition, the length of the complementary part is very short compared to the main part of the waveguide. For example, it represents around 1/10 or even 1/20 of the length of the horn and can represent 1/100 of the total length of the source.

THE Figures 1A and 1B represent an antenna source according to a first embodiment of the invention (embodiment not covered by the appended claims), the Figure 1A being a 3D view and the Figure 1B being a side view (seen from the exit of the horn). The antenna source 1 illustrated is in the form of a waveguide which comprises a first portion forming a horn 2 and a second portion forming a polarizer 3, the two forming a single part (waveguide) whose external shape is a cylinder straight with hexagonal base 10, the cylinder being hollow.

The horn 2 shown includes an input E _C (marked in Figure 3A ) and an S _C output. It has an external shape as a hexagonal cylinder 10, and comprises six ribs 21 (first ribs), which project towards the inside of said horn from of each edge 10A of the hexagonal cylinder 10 and extend in the longitudinal direction are staggered according to three steps 211, 212, 213 whose dimensions (heights, thicknesses and/or lengths) vary along the longitudinal direction entry and exit of the radiating element.

An important characteristic of the invention is that the external transverse dimensions of the main cylindrical part of the waveguide (here the hexagonal cylinder) do not vary in the longitudinal direction X and in particular do not decrease. These are the ribs inside the horn, with their steps, which make it possible to vary the impedance in said horn. Thus, this makes it possible to have the largest possible opening at the horn input to then be able to produce the septum polarizer which connects to the horn input. This makes it possible to introduce the polarizer blade and push the first upper mode as far as possible from the operating band of the array antenna. This particularity is even more true for cylindrical (or prismic) horns with a square base for which the cut-off frequency of the first higher mode appears for a lower frequency.

The horn is described in more detail in the remainder of the present description, according to different (non-limiting) variants, each of the variants being able to be implemented in the first embodiment, or in the second embodiment described below.

The polarizer 3 _has two inputs E _P1 , E _P2 separated by an internal blade 30, or septum, extending in the longitudinal direction Figure 4A ) which corresponds to the input E _C of the horn 2. The internal blade comprises several bearings 301, 302, 303, 304 in the longitudinal direction linear polarization electromagnetic field at the polarizer output, and vice versa. Regularly distributed on either side of the blade 30, at polarizer inlets E _P1 , E _P2 , four ribs 31 (second ribs) project towards the inside of said polarizer from each edge 10A of the hexagonal cylinder ₁₀ and extend in the longitudinal direction Figure 4A and 4B ) are formed, which correspond to the two radial ends of the blade 30 which disappears at the polarizer output. The second ribs 31, 32 have the same thicknesses and heights as the first steps 211 of the first ribs 21. In other words, at the output of the polarizer, the second ribs 31, 32 are in continuity with the first corresponding ribs 21 at the input of the horn 2. The dimensions of the second ribs are shown constant in the longitudinal direction, and are substantially equal to each other.

The ribs in the polarizer make it possible to reduce its minimum operating frequency and allow the propagation of the wave in it. The dimensions of the ribs are such that the main mode propagates in the polarizer. On the other hand, the cut-off frequency of the first higher mode must be greater than the maximum operating frequency so that it cannot propagate in the structure. In addition, this makes it possible to reduce the transverse dimensions of the polarizer compared to a conventional septum polarizer, in order to make it compatible with the opening of the horn.

The polarizer is described in more detail in the remainder of the present description, according to different (non-limiting) variants, each of the variants being able to be implemented in the first embodiment, or in the second embodiment described below.

THE figures 2A , 2B , 2C And 2D represent an antenna source according to a second embodiment of the invention which differs from the first mode in that it also comprises a third portion 4 which comprises a filter 40. Figure 2A is a 3D view, the Figure 2B is a sectional view along a plane passing through the X axis and the Y axis (corresponding to the plane of the blade), the Figure 2C is a sectional view along a plane passing through the X axis and the Z axis and the 2D figure being a side view (seen from the exit of the horn).

The antenna source 1' illustrated thus comprises a first portion forming a horn 2, a second portion forming a polarizer 3 and a third portion 4 comprising a filter 40, the three portions forming a single piece whose external shape is a straight cylinder with a base hexagonal 10.

The filter 40 corresponds to half of the right hexagonal cylinder in the third portion 4 (the output of the filter corresponds to one of the two inputs of the polarizer). Inside the half-cylinder, the filter comprises, in continuity with one of the two inputs of the polarizer, a series 42 of frequency filtering pads, the pads being positioned one after the other in the longitudinal direction X and arranged on the central blade. Filter pads are chosen to allow certain frequencies to pass while other frequencies are retained.

In the example shown, the pads have an inclination of 45° so that the antenna source is produced by additive manufacturing in a single piece, therefore in the same material as the horn and the polarizer. The different pads have dimensions (lengths, thicknesses and/or heights) which may differ from one pad to another. In addition, the distances between two adjacent pads may differ.

The dimensions of the pads as well as the distance between two adjacent pads are defined to make it possible to produce a “combline filter” type filter. A classic “combline” type filter is generally made by introducing metal rods into a rectangular guide, the size of the rods as well as the distance from the upper wall of the guide making it possible to transmit or reject certain frequencies. This type of filter is well known to those skilled in the art. According to the invention, the filter is dimensioned to produce a low-pass filter.

The third portion 4 further comprises third ribs 41 extending towards the interior thereof and over all or part of the length of said third portion. In the example shown, said third ribs are a continuation of the second ribs. These third ribs are dimensioned in such a way that the wave can propagate in the waveguide.

The filter is described in more detail in the remainder of this description, according to different possible variants (non-limiting). Any variation can be implemented in the second embodiment.

THE figures 3A (3D view) and 3B (side view) represent in detail a hexagonal horn 2 according to a first variant of the invention, which corresponds to the hexagonal horn of the figures 1A, 1B , 2A And 2B . The hexagonal horn 2 comprises six first ribs 21 which project towards the inside of said horn from each edge of the hexagonal cylinder. The first six ribs all have the same shapes, and they are shaped in steps along the longitudinal direction ) vary along the longitudinal direction, the thicknesses of the steps decreasing in the direction going from the entrance E _C towards the exit S _C of the horn (direction of circulation). Thus, the thickness e ₂₁₁ of the first step 211 is greater than the thickness e ₂₁₂ of the second step 212, itself greater than the thickness e ₂₁₃ of the third step. Furthermore, the height h ₂₁₁ of the first step 211 is slightly greater than the height h ₂₁₂ of the second step 212, itself greater than the height h ₂₁₃ of the third step 213.

Generally speaking, it is not necessary for the thicknesses and heights of the steps to vary in an increasing or decreasing manner in the direction of circulation, these being able to take any values as long as this allows the impedance variation to be carried out. desired.

Whatever the alternative embodiment, and more generally according to the invention, the number of steps as well as the dimensions of the steps of the first ribs are parameters configurable by those skilled in the art, so as to allow a given impedance variation between the entrance and exit of the horn. Thus, there are a very large number of possible configurations, not all of which can be described in the present description. For example, the number of steps can be equal to three as illustrated or four.

Furthermore, the number of first ribs and their locations are not limited to the modes and variants illustrated.

The first ribs may have all the same shapes, as shown, or may have different shapes.

Preferably, the number of first ribs is an even number, both at the inlet and outlet of the horn, and they are arranged regularly around the perimeter of the cylinder. An even number favors symmetry of the antenna source. The even number then favors the introduction of the blade of the septum polarizer which in this case attaches to two opposite ribs and makes it possible to simplify the dimensioning of the septum polarizer.

According to a particular embodiment, a final section without rib (step of zero height) can be added at the level of the outlet of the horn in order to improve the efficiency and directivity of the latter (these two notions are well known of those skilled in the art). In particular if the horn has a complementary part, for example in the shape of a cone or a truncated pyramid, at the outlet of said horn, this complementary part does not have a rib.

THE figures 4A (3D view in the input-output direction of the polarizer), 4B (3D view in the output-input direction of the polarizer) and 4C (side view) represent a hexagonal polarizer according to the first variant of the invention, which corresponds to the polarizer hexagonal figures 1A, 1B , 2A And 2B . The hexagonal polarizer 3 has two inputs E _P1 , E _P2 separated by an internal blade 30, or septum, extending in the longitudinal direction a width l ₃₀ . The internal blade 30 comprises four bearings 301, 302, 303, 304 configured to transform an electromagnetic field of circular polarization at the input into an electromagnetic field of linear polarization at the output, and vice versa. But this number of levels is not limiting and can be less than four (two or three) or five or more.

On either side of the blade 30, at polarizer inlets E _P1 , E _P2 , four second ribs 31 project towards the inside of said polarizer from each edge of the hexagonal cylinder and extend in the longitudinal direction X In addition, at the outlet S _P of the polarizer, two additional bearings on the two radial ends of the internal blade (ends located on the edges of the cylinder) form two second complementary ribs 32 at the outlet S _P of the polarizer. In other words, at the output of the polarizer, these two second complementary ribs 32 formed at the output of the polarizer correspond to the two ends of the blade 30 which disappears at the output of said polarizer.

The thicknesses e ₃₁ and the heights h ₃₁ of the four second ribs 31 are constant in the longitudinal direction and are substantially equal to each other. The thicknesses e ₃₂ and the heights h ₃₂ of the two second complementary ribs 32 are constant in the longitudinal direction and are substantially equal to each other and to those of the four second ribs 31.

Whatever the alternative embodiment, and more generally according to the invention, the number of bearings of the internal blade, as well as the thickness of the blade, and the dimensions of the bearings are configurable by those skilled in the art. The polarizer blade may also have shapes different from that shown. In addition to the illustrated stepped shape, we find in the literature a large number of shapes other than the stepped shape, shapes which can also be used in the context of the invention. We can cite for example a blade whose shape has been approximated by a mathematical equation of the Legendre polynomial type. Any other form adapted to the function of transforming an electromagnetic field of linear polarization into an electromagnetic field of circular polarization, and vice versa, can be considered. Thus, there are a very large number of possible configurations, not all of which can be described in the present description.

Preferably, the thickness e ₃₀ of the internal blade 30 is substantially equal to the thickness e ₃₁ , e ₃₂ of the second ribs 31, 32. This makes it possible to facilitate the design and manufacture of the antenna source, and to the network antenna, and to promote the symmetry of the whole.

Preferably, the thickness e ₃₁ , e ₃₂ (and/or the height h ₃₁ , h ₃₂ ) of the second ribs 31, 32 is substantially equal to the thickness e ₂₁₁ (and/or the height h ₂₁₁ ) of the first ribs 21 (first step 211) at the entrance to the horn. The second ribs 31 can thus be positioned in continuity with the first ribs 21 at the entrance E _C of the horn 2.

THE figures 5A (3D view), 5B (side view) and 5C (another 3D view) represent in detail a filter, which corresponds to filter 40 of the figures 2A And 2B .

The filter is only formed on one of the polarizer inputs because the antenna operates in mono-polarization.

The filter 40 corresponds to half of the right hexagonal cylinder in the third portion 4 (the output of the filter corresponds to one of the two inputs of the polarizer). Inside the half-cylinder, the filter comprises, in continuity with one of the two inputs of the polarizer, a series 42 of four frequency filtering pads 421, 422, 423, 424, the pads being positioned one after the other in the longitudinal direction X and arranged on the internal blade 30 (extended between the polarizer and the third portion). Filter pads are chosen to allow certain frequencies to pass while other frequencies are retained.

The different pads have dimensions (lengths, thicknesses and/or heights) which may differ from one pad to another. In addition, the distances between two adjacent pads may differ.

In the example illustrated, the second and third studs 422, 423 have equivalent dimensions (thickness e ₄₂₂ , height h ₄₂₂ , length L ₄₂₂ ), and the first and fourth studs 421, 424 also have equivalent dimensions (thickness e ₄₂₁ , height h ₄₂₁ , length L ₄₂₁ ) but different from the second and third studs. In addition, the four studs are spaced from each other by distances which are not necessarily equal.

The number of pads illustrated is not limiting, the same goes for the dimensions of the pads as well as the distances between adjacent pads.

As indicated previously, the dimensions of the pads as well as the distance between two adjacent pads are defined to make it possible to produce a filter of the "combline filter" type of low-pass filter, the shape of which can be adapted in order to integrate it into the wrinkled waveguide.

In addition, the dimensions and number of pads depend on the desired value for filter rejection. If we want to increase the rejection level, we increase the number of pads.

The third portion 4 further comprises third ribs 41 extending inwards and over all or part of the length of said third portion, said third ribs being in continuity with the second ribs 31, 32. These third ribs are dimensioned in such a way that the wave can propagate in the waveguide.

The shape of the polarizer being very variable, and depending on the shape of the horn (cylinder with circular or polygonal base, etc.), we can have a wide variety of shapes for the ribbed waveguide forming the filter. Possible, non-limiting forms are illustrated in the Figure 11 (shown with the ribs but without the studs).

Furthermore, in order to facilitate the insertion of the pads in the center of the filter, it is possible to provide a transition between the polarizer and the filter which will make it possible to change the arrangement of the ribs inside the third portion comprising the guide. wave including the filter. One condition is to ensure that the operating frequency of the waveguide is lower than the minimum operating frequency, both before and after the transition. As illustrated in the Figures 12A to 12C , the transition can be made by removing ribs ( Figure 12A ), adding ribs ( Figure 12B ), or by bending existing ribs ( Figure 12C ), or even by combining several of these solutions.

THE figures 6A (3D view) and 6B (side view) represent a hexagonal horn 2' according to a second variant of the invention, which differs from the first variant in that the first ribs 21' are not arranged at the level of the edges of the cylinder hexagonal 10 but in the middle of the side surfaces 10B of said cylinder. In the example shown, there are six first ribs with three steps each, the steps decreasing between the entrance and exit of the horn but, as previously stated, it is not necessary for the thicknesses and heights of the steps to vary increasing or decreasing in the direction of circulation, these can take any values as long as this makes it possible to achieve the desired impedance variation.

The number of first ribs and steps is not limiting. Preferably there is an even number of first ribs, both at the entrance and exit of the horn.

THE figures 7A (3D view in the input-output direction of the polarizer), 7B (3D view in the output-input direction of the polarizer) and 7C (side view) represent a hexagonal polarizer 3' according to the second variant of the invention, which differs of the first variant in that the second ribs 31', 32' as well as the internal blade 30 are not arranged at the level of the edges of the hexagonal cylinder but in the middle of the lateral surfaces of said cylinder. In the example shown, there are six first ribs with three steps each. But the number of ribs is not limiting. Preferably there is an even number of second ribs, both at the input and output of the polarizer.

The first and second variants can be combined with each other, so that the first ribs (and the second ribs) can be arranged both at the edges of the hexagonal cylinder and in the middle of the side surfaces of said cylinder. We can thus obtain, for example, 12 first ribs in the horn and 12 second ribs at the polarizer output.

The second ribs are generally arranged at the same locations over the entire length occupied by said second ribs.

The first ribs can be arranged in the same locations along the entire length occupied by the first ribs, as illustrated.

Alternatively, the first ribs can be positioned in a first configuration on a first length (or first section), then in a second configuration on a second length (or second section), then possibly again in a third configuration on a third length (or third section) etc. However, it is important to respect the impedance steps and to respect the best possible symmetry of the horn (and the antenna source) in relation to the longitudinal axis X.

An example of this alternative (third variant) is illustrated in figure 8 which represents a horn 3‴ in which first ribs 21 (configured in a single step) are positioned on the edges of a straight hexagonal cylinder at the entrance E _C of the horn on a first section L1 then first ribs 21' (configured in three steps) are positioned in the middle of the lateral surfaces of the hexagonal cylinder on a second section L2 which can go as far as the outlet S _C of the horn. This configuration is obviously not limiting.

In a preferred embodiment, the second ribs at the output of the polarizer are positioned in continuity with the first ribs at the input of the horn. Alternatively, it is possible to consider a change in the location of the ribs between the output of the polarizer and the entrance of the horn (for example at the level of the polarizer edges then on the middle of the horn surfaces or vice versa), always in the limit of respecting the desired impedances.

THE figures 9A (3D view) and 9B (side view) represent a 2" horn according to a fourth variant of the invention, which differs from the first, the second variant and the third variant in that the right cylinder 10' is circular and no hexagonal. The first 21" ribs are positioned regularly around the circle. In the example shown, there are six first 21" ribs with three steps each. But the number of ribs and steps is not limiting. Preferably there is an even number of first ribs, both at the entrance and exit of the horn.

THE figures 10A (3D view in the input-output direction of the polarizer), 10B (3D view in the output-input direction of the polarizer) and 10C (side view) represent a 3" polarizer according to the fourth variant of the invention, which differs from the first, the second variant and the third variant in that the right cylinder 10' is circular and not hexagonal. The second ribs 31", 32" and the internal blade 30" are positioned regularly around the perimeter of the circle . In the example shown, there are four second ribs 31" at the polarizer input and six second ribs 31", 32" at the polarizer output. But the number of ribs is not limiting, preferably there is a number pair of second ribs, both at the input and output of the polarizer.

The shape of the right cylinder is not limited to hexagonal or circular shape. Alternatively, the shape of the right cylinder can be square, octagonal, decagonal, and more generally in the shape of a regular polygon of even order (even number of sides), in order to present the most symmetrical shape possible.

Additionally, in order to maintain circular polarization, the ribs must be positioned symmetrically around the perimeter of the cylinder.

• pour un cylindre carré, le nombre de premières nervures peut être de 4, 8, 12 ... ;
• pour un cylindre hexagonal, le nombre de premières nervures peut être de 6, 12 ...
• pour un cylindre octogonal, le nombre de premières nervures peut être de 8, 16....
• pour un cylindre décagonal, le nombre de premières nervures peut être de 10, 20

Thus, preferably for a cylinder with a polygonal base, the number of first ribs in the horn is equal to the number of sides of the polygon, or to a multiple of the number of sides. For example :

• for a square cylinder, the number of first ribs can be 4, 8, 12...;
• for a hexagonal cylinder, the number of first ribs can be 6, 12...
• for an octagonal cylinder, the number of first ribs can be 8, 16....
• for a decagonal cylinder, the number of first ribs can be 10, 20

The number of first ribs indicated above is given for the entrance and exit of the horn. For the polarizer, the number of second ribs indicated above corresponds to the number of ribs at the output of it (at the input of polarizer there are two less corresponding to the blade). Likewise, when there is a filter, there are two less third ribs corresponding to the blade which extends into the filter. Thus, for a hexagonal cylinder, we preferably have 6 first ribs at the entrance and exit of the horn, 6 second ribs at the outlet of the polarizer (corresponding to the entrance to the horn), 4 second ribs at the entrance to the polarizer, and 4 third ribs at the inlet and outlet of the filter, if applicable.

The ribs (and the internal blade) can be positioned at the interior edges and/or on the interior side surfaces of the polygon, preferably in the middle of the interior side surfaces of the polygon.

For a circular cylinder, the ribs (and the internal blade) are also distributed regularly around the perimeter of the circle, inside said circular cylinder. The number of first ribs, second ribs, or even third ribs when there is a filter, can be 4, 6, 8, 10...

For a circular cylinder, there are preferably 6 first ribs at the entrance and exit of the horn, 6 second ribs at the outlet of the polarizer (corresponding to the entrance to the horn), 4 second ribs at the entrance to the polarizer, and 4 third ribs at inlet and outlet of the filter, if applicable.

More generally, the number of first ribs, as well as second ribs, or even third ribs when there is a filter, is preferably an even number, preferably at the input and output of the horn, the polarizer, and the filter if applicable.

The horn and the polarizer being in one piece (waveguide), with the same external shape, the shape of the horn determines the shape of the polarizer. So, if the horn is hexagonal, square, circular, the polarizer is too. Likewise, when a filter is added, the external shape of the third portion which includes the filter respects the external shape of the horn and the polarizer.

There figure 13 represents in 3D view (view from the outlet of the horns) a radiating panel 110 for an array antenna, comprising a plurality of sources according to the invention. In the example shown, the sources 1 all have the shape of a straight hexagonal cylinder 10, the first ribs 21' being on the middle of the side surfaces of said cylinder. The radiant panel shown is in one piece. The number of sources represented here is 37 but it is not in nothing limiting, and it is generally much higher. In addition, the sources can be chosen according to any of the modes, variants, alternatives described above.

Preferably, the sources of the same radiating panel are all substantially identical.

The structure of the radiating panel being complex, and the sources having small dimensions (of the order of 10 cm in height, 15 cm in width and 20 cm in length), a preferred solution for manufacturing the radiating panel is additive manufacturing.

An additive manufacturing technique particularly suited to manufacturing the radiant panel is the selective laser melting technique known as “SLM” (for “Selective Laser Melting” in English), also called “LBM” (for “Laser Beam Melting” in English). . The SLM technique consists of depositing a layer of metal powder of controlled thickness (and generally under a controlled atmosphere) on a manufacturing plate, using a laser source to carry out selective fusion of the powder in the manufacturing plane, then depositing another layer of powder on the previous layer, the manufacturing iteration continuing to form the desired part. A titanium or aluminum metal powder can be used, although this is not limiting.

The SLM technique allows the manufacturing of complex parts, while reducing manufacturing time and costs. Such a radiating panel with a plurality of sources is not achievable with certain conventional manufacturing methods (milling type, etc.) or involves a complex, long manufacturing process with high manufacturing costs with other manufacturing methods. conventional (electric erosion type, etc.).

Alternatively to the SLM technique, we can consider an additive manufacturing technique based on the use of polymers, for example the additive manufacturing technique by material extrusion (“Material Extrusion” also called “Fused Deposition Modeling” or “FDM” in English) according to which at least one heated print head extrudes a polymer matrix filament so as to manufacture a part; moving the print head along the three axes allows small volumes of molten polymer to be deposited locally and build a piece layer by layer. We can also cite additive manufacturing by material jet (“Material Jetting” in English) which is a process in which at least one print head movable along the three axes projects a photosensitive polymer, which plays the role of an ink , which is then polymerized by UV radiation. Other techniques exist which are not mentioned here but which are well known to those skilled in the art. Whatever the additive manufacturing technique based on the use of polymers, the part produced must be metallized (deposition of a metallization layer).

Even with the SLM technique, and in order to reduce RF losses, a metallization layer is preferably produced on the part.

The metallization layer can be produced using an electrolytic deposition or a chemical deposition, for example depending on the shape of the part and/or the intended field of use.

In order to facilitate the additive manufacturing of a radiating panel, it is possible to adapt the production of certain elements of the sources.

Thus, the pads 421, 422, 423 of the filters 4 can have an inclination (maximum inclination of 45°), as illustrated in the figures 14A (filter 4' comprising pads 421', 422', 423' without inclination) and 14B (filter 4 with inclination).

In addition, under all or part of the steps 211, 212, 213 of the horns 2, it is possible to add material to make a support 221, 222 as illustrated in the figures 15A (without support) and 15B (with support). Such a support for such a part which is manufactured vertically makes it possible to avoid collapse during manufacturing. Such support is a technique commonly used in additive manufacturing.

As an alternative to an additive manufacturing technique, a solution for manufacturing a radiant panel is the die casting technique. Die Casting is a metal casting process that involves forcing molten metal under high pressure into a mold cavity. The mold cavity is created using two hardened steel dies that have been machined into shape and function similar to an injection mold during the process. Most castings pressure are made from non-ferrous metals, particularly zinc, copper, aluminum, magnesium, lead, tin and tin-based alloys. Depending on the type of metal being cast, a hot or cold chamber machine is used.

There Figure 16 schematizes a functional architecture of a direct radiation network antenna 100 which comprises a radiating panel 110 comprising several sources 1' (each source 1' is represented with a horn 2, a polarizer 3 and a filter 4), such as the radiating panel illustrated in the figure 13 . The radiating panel 110 is connected to amplifiers 120 and/or loads 121. The assembly is connected to a network former 140 or “BFN” for “Beam Forming Network” which makes it possible to distribute the energy (in amplitude and in phase) between the different sources to direct the antenna beam in a given direction.

A load absorbs the RF energy it receives and dissipates it in the form of heat.

This involves making electrically conductive connections 130 between all or part of the sources of the radiating panel and the amplifiers and/or loads. The thickness of metal (or metallization) of the sources of the radiating panel being low (generally one millimeter or less), it is difficult to make these connections in said thickness, so we use locations in the network of sources. In the case of a limited number of sources (typically around fifty sources), the connections can be placed on the edges of the network. If the number of sources is greater, the connections will be placed more inside the network.

THE figures 17 And 18 illustrate a radiating panel 110, such as the radiating panel illustrated in the figure 13 (with more sources), seen from the filter input.

The radiant panel shown has 256 radiating elements. It therefore has 512 input ports to the septum polarizers. For example, access E _P1 (see identification for example in figure 4A ) of the septum polarizer generates left circular polarization (PCG) and access E _P2 (see marking for example in figure 4A ) of the septum polarizer generates right circular polarization (PCD): thus 256 accesses at the input of the radiating panel generate right circular polarization and 256 accesses generate left circular polarization. The antenna is generally designed to operate in mono-polarization and for the case presented in this example in right-hand polarization. In the case considered, the right polarization is called "main polarization" and the left polarization "cross polarization". In the case considered, the 256 E _P2 accesses are followed by filters then they must be connected to the amplifiers to generate the signal. The 256 E _P1 ports are not followed by filters and must be connected to loads to limit the cross component which corresponds to noise.

To connect the amplifiers to the radiating panel, it is necessary to have locations with threads inside the radiating panel. For this two solutions were considered, including Figure 17 illustrates a first solution (connection 131), the second solution being illustrated in Figure 18 (connection 132).

The first connection mode 131 illustrated in Figure 17 uses some cross polarization ports (access E _P1 of the polarizers in the case considered) which are filled with material to be able to have a tapping in order to connect the amplifiers to the radiating panels with screws.

The second connection mode 132 illustrated in Figure 18 uses the 2 ports of the same source (access E _P1 and E _P2 of the polarizers in the case considered) which are filled with material to be able to have a tapping in order to connect the amplifiers to the radiating panels with screws.

In both modes, the connections form short circuits.

In the case where the antenna is designed to operate in left polarization, then the 256 accesses E _P1 are followed by filters then connected to the amplifiers and the 256 accesses E _P2 are not followed by filters and are connected to loads.

Whatever the connection mode used, the amplifiers are preferably grouped into block(s) of several amplifiers, a block which can be designated as an “amplification module”. The connection of the amplification modules to the radiating panel is therefore done via fixings which are fixed at the level of the connections made, for example screws which are screwed into the threads of the connections. The connections can be made at the time of manufacturing the radiant panel (for example during additive manufacturing) or after manufacturing (for example by tapping once the radiant panel has been manufactured).

The first connection mode does not degrade RF performance too much compared to the second connection mode but requires more compact amplification modules. The second connection method is easier to achieve.

The number of amplifiers in an amplification module (and consequently the number of short circuits at the radiating panel output) depends on several parameters and objectives: it may be to facilitate the production and assembly of the antenna with the aim of reducing the cost of the antenna, or to target RF performance for the antenna (the greater the number of short circuits, the more the RF performance is degraded), or even to integrate thermal control ( the aim of thermal control being to evacuate the power dissipated by the amplifiers out of the antenna).

The mode of transmission of microwave (HF) waves in the amplifiers and in the radiating panel are different. In fact, the waves at the output of the radiating panel are transmitted via a wave guide (ridged) while the waves in the amplifier generally propagate using a line called a “microstrip line”. » or “microstrip line” which is a microwave transmission line known to those skilled in the art and will not be developed here.

The transition from the HF wave propagation mode to a wrinkled waveguide from the radiating panel to the microstrip line of the amplifiers must be carried out via a suitable transition. The so-called “Vivaldi” antipodal transition makes it possible to make a transition between a waveguide and a microstrip line, but it is generally implemented for a classic, non-ridged waveguide. Its principle illustrated in figures 19A And 19B .

A so-called “Vivaldi” antipodal transition 50 consists of the insertion of a substrate 51 inside the waveguide 55 (generally in the middle of the waveguide). Two different metal engravings are formed on the substrate, a first engraving 51 on its upper face (its end farthest from the entrance of the waveguide is refined in the form of a conductive ribbon 51A) and a second engraving 52 on its lower face (its end farthest from the entrance to the waveguide is widened to become the ground plane 52A). The electric field E arrives at the level of the engraved substrate which captures the electric field, then between the two metal engravings. The shape of the metal engravings makes it possible to rotate the electric field and transmit it to the conductive ribbon.

The inventors have developed a new transition based on the Vivaldi antipodal transition. The principle is to create a preliminary transition part making it possible to change the position, dimensions and/or shapes of the ribs of the waveguide at the input of the source (at the input of the polarizer or filter) to free up space for the center of it. An example of carrying out such a preliminary transition 60 is illustrated in figures 20A , 20B and 20C . There Figure 20A shows a side view of the output 60A of the transition (for example at the filter input) where the ribs 41 of the filter 4 appear. figure 20B represents in side view the input 60B of the transition/adaptation (amplifier side). There Figure 20C represents in 3D view the transition/adaptation 60 in the continuity of the filter.

This makes it possible to place the substrate of the Vivaldi 50 transition in the center of the waveguide, with the two metallic etchings, as illustrated in Figure 21 .

Loads can be connected to radiant panels in the same way. The loads are in fact generally integrated into the amplification module and can be connected in the same way as the amplifiers to the radiating panel, with the same guide transition/adaptation and the same Vivaldi transition. The load can be connected to the end of the microstrip line as a surface mounted component (SMT).

This makes it possible to form the array antenna, with the targeted RF performance.

The present invention is not limited to the embodiments previously described but extends to any embodiment falling within the scope of the claims.

The invention finds applications in the field of network space antennas for satellites in low orbit where data must be transmitted in a large angular range, in particular in the K, Ka, Ku, Q, V bands, etc. by example for high-speed internet.

Claims (13)

1. An antenna feed (1') for a direct radiating array antenna, for the transmission and the reception of microwaves, said feed comprising a waveguide having at least one main part (10, 10') in hollow straight cylinder shape extending in a longitudinal direction (X), the base of said cylinder having at least one axis of symmetry in its plane and the outer transverse dimensions of said main part being constant in the longitudinal direction (X);

   the main part of the waveguide comprising, in said longitudinal direction:

   - a first portion forming a radiating element (2, 2', 2", 2‴), or the major part of said radiating element, said radiating element comprising first ridges (21, 21', 21") extending inwards and over all or part of the length of said radiating element, said first ridges being regularly distributed around the perimeter of said radiating element and each having several treads (211, 212, 213) along the longitudinal direction (X), the number, the heights (h₂₁₁, h₂₁₂, h₂₁₃) and the thicknesses (e₂₁₁, e₂₁₂, e₂₁₃) of said treads being configured to allow a given variation, preferably an increase, of impedance between an input (Ec) and an output (Sc) of the radiating element;

   - a second portion forming a polarizer (3, 3', 3"), said polarizer having two inputs (E_P1, E_P2) separated by an internal leaf (30, 30', 30") extending in the longitudinal direction (X), and an output (S_P) corresponding to the input (E_C) of the radiating element (2, 2', 2", 2‴), the internal leaf having several levels (301, 302, 303, 304) along the longitudinal direction (X), said levels being configured to transform a circularly polarized electromagnetic field at the input into a linearly polarized electromagnetic field at the output, and, in reverse, to transform a linearly polarized electromagnetic field at the output into a circularly polarized electromagnetic field at the input, the polarizer further comprising second ridges (31, 32, 31', 32', 31", 32") extending inwards and over all or part of the length of said polarizer, said second ridges and said internal leaf being regularly distributed around the perimeter of said polarizer;

   - a third portion (4) comprising a filter (40, 40'), the internal leaf (30, 30', 30") being extended in all or part of said third portion, the filter (40, 40') comprising a set (42) of frequency filtration pads (421, 422, 423, 424, 421', 422', 423') arranged inside the third portion and on one and the same surface of the internal leaf, the output (S_F) of the filter corresponding to one of the two inputs (E_P1, E_P2) of the polarizer, said third portion further comprising third ridges (41) extending inwardly and over all or part of the length of said third portion, said third ridges and the internal leaf being evenly distributed around the perimeter of said third portion;

   the radiating element, the polarizer and the filter being in a single piece, preferably produced using an additive manufacturing technique, and the polarizer and filter being arranged end-to-end in the longitudinal direction.
2. The antenna feed (1') according to claim 1, the waveguide having a constant thickness over all of its length.
3. The antenna feed (1') according to claim 1 or claim 2, the number of first ridges and/or of second ridges being an even number, preferably both at the input and at the output of the radiating element and/or of the polarizer.
4. The antenna feed (1') according to one of claims 1 to 3, the base of the straight cylinder (10) being a regular polygon of even order, preferably a hexagon.
5. The antenna feed (1') according to claim 4, the internal leaf and all or part of the first ridges and/or of the second ridges being disposed at the edges of the polygonal straight cylinder.
6. The antenna feed (1') according to claim 4, the internal leaf and all or part of the first ridges and/or of the second ridges being disposed on the internal lateral surfaces of the polygonal straight cylinder.
7. The antenna feed (1') according to one of claims 1 to 3, the base of the straight cylinder (10') being a circle.
8. The antenna feed (1') according to any one of claims 1 to 7, the number of third ridges being an even number, preferably both at the input and at the output of the filter.
9. The antenna feed (1') according to any one of claims 1 to 8, the waveguide being entirely in hollow straight cylinder shape over all of its length.
10. The antenna feed according to any one of claims 1 to 8, the waveguide comprising the main part in hollow straight cylinder shape and a complementary part, wherein said complementary part may be in cone or truncated pyramid shape at the output of the radiating element, the most flared part being disposed at the output of the radiating element, the complementary part being free of grooves.
11. A radiating panel (110) for a direct radiating array antenna comprising:

    - a plurality of antenna feeds (1') chosen according to any one of claims 1 to 10;
    said radiating panel being in a single piece, preferably produced using an additive manufacturing technique.
12. A direct radiating array antenna (100) comprising:

    - a radiating panel (110) according to claim 11;

    - at least one amplifier (120) and/or one load (121) connected to the radiating panel, at the input (E_F) of at least one filter (40) of one of the antenna feeds (1') of the plurality of antenna feeds.
13. The array antenna (100) according to claim 12, the radiating panel (110) being connected to the at least one amplifier (120) and/or the at least one load (121) via at least one Vivaldi antipodal transition (50), and preferably via at least one transition/adaptation (60) designed to change the position, the dimensions and/or the shape of the ridges of the waveguide at the input of the feed so as to be able to position the Vivaldi transition (50) within said waveguide.

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